The invention relates to silanised, structurally modified, pyrogenically produced silicas, a process for the production thereof and their use.
Silanised silicas are used as thickeners, such as e.g. for water-thinnable lacquers and resins, such as e.g. epoxy resins.
From EP 0 672 731 B1, silanised, pyrogenically produced silicas are known, which are characterised in that the pyrogenically produced silicas are treated with a compound from the group (RO)3SiCnH2n+1, wherein n=10 to 18 and R=short-chained alkyl radicals. For example, the pyrogenically produced silicas have been treated with the compound (CH3O)3SiC16H33 (hexadecyltrimethoxysilane) or with the compound (CH3O)3SiC18H37 (octadecyltrimethoxysilane).
The production of the silanised, pyrogenically produced silicas takes place in that the pyrogenically produced silicas are placed in a mixer, the silicas are sprayed, optionally first with water and then with the compound from the group (RO)3SiCnH2n+1 while mixing intensively, mixed for a further 15 to 30 minutes and then tempered at a temperature of 100 to 160° C. for a period of 1 to 3 hours.